Various optical disks have recently been proposed as disk type recording media that are recordable and removable from a recording and reproducing apparatus. Such recordable optical disks are proposed as large-capacity media having a capacity of a few gigabytes or more, and receive high expectations as media for recording AV (Audio Visual) signals such as video signals and the like.
As a source (source of supply) of digital AV signals recorded on the recordable optical disks, there is digital satellite broadcasting typified by CS (Communication Satellite) digital broadcasting and BS (Broadcasting Satellite) digital broadcasting in Japan, for example. In addition, digital terrestrial television broadcasting and the like are being considered for the future.
Digital video signals supplied from these sources are typically video-compressed by an MPEG (Moving Picture Experts Group)-2 Video system. Also, in a recording apparatus, a recording rate specific to the apparatus is generally determined. When a digital video signal from a digital broadcast is recorded on conventional video storage media for consumer use, in an analog recording system, the digital video signal is decoded, subjected to digital-to-analog conversion and band limitation, and recorded. In a digital recording system such as an MPEG-1 Video system, an MPEG-2 Video system, a DV (Digital Video) system or the like, on the other hand, the digital video signal is decoded by a tuner, then re-encoded using an encoding system and a recording rate specific to the recording apparatus, and recorded.
However, such recording methods involve degradation in picture quality because the supplied bit stream is decoded, thereafter subjected to band limitation or re-encoding, and then recorded. When a video-compressed digital signal is recorded and a transmission rate of the video-compressed digital signal exceeds a recording rate of the disk, the recording and reproducing apparatus needs to decode the digital signal, thereafter re-encode the digital signal so as to decrease the transmission rate to an upper limit of the recording rate of the disk or lower, and then record the digital signal. However, when the transmission rate of the input digital signal does not exceed the recording rate of the recording and reproducing apparatus, the degradation in picture quality is minimized by a method of recording the supplied bit stream as it is without decoding or re-encoding the bit stream.
Digital signals are characterized in that the transmission rate is not always constant. When a digital signal is transmitted by a variable rate system in which the bit rate of the digital signal fluctuates with time, a tape recording system having a fixed recording rate because of a fixed rotational speed of a rotary head maintains a constant bit rate at all times by stuffing empty packets, for example. This means recording at a maximum bit rate at all times and hence wasteful consumption of recording capacity. On the other hand, a disk recording apparatus temporarily stores data in a buffer, and records the data onto a disk on a burst and an intermittent basis. Hence, the disk recording apparatus eliminates the need for inserting empty packets, and can therefore use capacity on a recording medium less wastefully.
Thus, a recording and reproducing apparatus that records a digital broadcast signal as it is without decoding or re-encoding the digital broadcast signal as with a data streamer and uses a disk as a recording medium is expected to be desired in the future when digital broadcasting will become mainstream.
In the present invention, a unit in which a user selects and reproduces AV data (a unit in which the user tacitly expects reproduction to be performed continuously) is referred to as a playlist. A simplest example of the playlist is continuous video (contents) from a start of recording to an end of the recording.
A function of preventing an entire disk or playlists recorded on the disk from being readily reproduced is considered. A mechanism that sets a code number and does not allow reproduction unless the code number is inputted is useful when there are contents not desired to be viewed by others and when there is a playlist not desired to be changed.